The present invention relates to a remote control for the wireless transmission of control commands from a transmitter to at least one receiver, in particular for the remote control of several garage doors, in accordance with an encoding device provided in the transmitter which effects the encoding of the control commands to be transmitted.
Particularly with the underground car-parks of fairly large residential estates, it has now become usual to have electrical operation of the garage doors closing off access to the underground car-park and to operate the garage doors by means of a remote control. To prevent any unauthorized opening or closing of the garage doors, diverse remote controls of the type first mentioned are known.
Patent specification DE 29 23 962 C2 discloses a remote control where a specific code can be set or preset in the transmitter. The control commands to be transmitted are encoded by the code in an encoding device on the transmitter side so that only the designated receiver responds to the control commands transmitted. By means of a signal change-over facility in the receiver, this can be initialized with the code on the transmitter side being able to be transferred to and stored on the receiver. To ensure that the code in the receiver can only be initialized by authorized persons, it is provided that the signal change-over facility on the receiver side can be manually actuated by means of an element inaccessible to non-authorized persons.
Patent specification DE 33 32 761 C2 discloses another possibility to protect the remote control from unauthorized use. Security against unauthorized persons is achieved by providing a (quasi) random generator at the receiver for code generation and by a temporary data link being able to be set up to transfer the code from the receiver to the transmitter.
Both of the above remote controls have the disadvantage that they can only be used for a specific garage door. However, a remote control is desirable which can be used for different user groups and for different garage doors. Such a remote control is known from patent specification DE 36 25 555 C2. To allow the transmitter of the remote control to be used for different receivers, the receiver is fitted with a memory location option switch which can be used to select a memory location when the code of the corresponding transmitter is to be transmitted to the receiver. The receiver can thus be initialized for several codes so that control commands from different transmitters with different codes can be evaluated. One substantial disadvantage of this remote control can be found in the fact that several codes have to be evaluated by the receiver. Due to the limited computation capacity of the microprocessor used, the number of transmitters which can be evaluated is therefore also limited. A further disadvantage of such a remote control is that the fixed-position receiver can only be initialized in an awkward and complex manner.